@article{JOLT_2017_27_3_a7,
     author = {Matvei Libine},
     title = {The {Two-Loop} {Ladder} {Diagram} and {Representations} of {U(2,2)}},
     journal = {Journal of Lie Theory},
     pages = {771--800},
     year = {2017},
     volume = {27},
     number = {3},
     url = {http://geodesic.mathdoc.fr/item/JOLT_2017_27_3_a7/}
}